The invention relates to a masonry fireplace operating on the secondary fire chamber principle, particularly a baking oven, comprising: a furnace in which the fuel is burnt and the bottom of which is formed by a baking grate, the furnace being provided with an oven door positioned in the front wall of the oven; an ash chest positioned below the furnace and provided with an ash door; a secondary fire chamber positioned above the furnace and into which a throat leads from the back portion of the furnace; and substantially vertical cheek flues extending downwards from the secondary fire chamber on both sides of the oven door.
When masonry fireplaces began to become popular in the 1970's, it became necessary to gain reliable information on the operation of fireplaces and the requirements they set for the materials and structures thereof. Such experiments have led to the introduction of the secondary fire chamber in baking ovens, too. The use of the secondary fire chamber provides a substantially clean combustion, high coefficient of effeciency, and the oven is also easy to manufacture. However, when planning new fireplaces, a higher coefficient of efficiency has constantly been aimed at.
Also, the position and operation of the coal dropping door causes problems in prior baking ovens. Since the coal dropping door is generally positioned immediately behind the oven door, there is a risk that coals fall out of the oven door on the operator. This kind of door also decreases the baking area of the oven.